This invention relates in general to structures such as load bearing frames and trusses and more particularly to structures that provide an enhanced trade off between the stress that can be safely carried in relation to the amount of material required for the structure.
This enhanced strength to weight ratio is a goal of a large number of designs including many of those proposed and constructed by Richard Buckminster Fuller. In most contexts where load bearing frames and trusses are employed, failure occurs because of a failure in tension rather than in compression. Although the loads imposed primarily induce compressive stress in the material, that stress is resolved within the material by vectors which introduce tension. For example, a dome subject to load will tend to deflect in such a fashion as to introduce tension along the trusses that constitute the dome. Failure will occur because of a failure in tension. Much attention has been paid to developing materials which have great tensile strength for use in load bearing structures in such a way as to employ the tensile strength of these materials so that loads supplied will be resolved, at least in part, by the tension created in these tension members. Such an approach is outlined in the Buckminster Fuller U.S. Pat. No. 3,354,591 issued in 1967. A more recent improvement on that structure is set forth in U.S. Pat. No. 4,207,715 issued in 1980. This combination of tension and compression members is also disclosed in the structure shown in U.S. Pat. No. 4,711,062 issued in 1987.